The present invention generally relates to a moisture control construction material and, more particularly, to a moisture control construction material enhanced in decorativeness and improved in stain-resistance by glazing surfaces thereof.
Japanese houses have achieved good moisture-controllability and water-vapor-resistance by employing wooden construction including mud walls. In recent years, highly-airtight-sealing of buildings has been promoted. This results in frequent use of what are called xe2x80x9cnew construction materialsxe2x80x9d developed by putting importance on moisture-controllability and water-vapor-resistance. Such xe2x80x9cnew construction materialsxe2x80x9d, however, are insufficient in moisture-controllability and water-vapor-resistance characteristics, so that the following problems have arisen.
(i) Condensation occurring on the surface of such a xe2x80x9cnew construction materialxe2x80x9d impairs the comfortableness and durability of a building.
(ii) Moisture content due to the condensation results in growth of molds and mites.
To solve these problems, buildings are usually provided with an air conditioning system. Such an air conditioning system, however, requires electric power. Therefore, the use of such xe2x80x9cnew construction materialsxe2x80x9d is undesirable from the viewpoint of the costs of equipment and running costs.
Construction materials having a capability of moisture control have been developed so that humidity in a room is controlled without an air conditioning system and electric power and so that sufficient water-vapor-resistance is obtained. A kind of moisture controlling building materials are prepared by mixing materials having moisture absorbing and desorbing properties such as zeolite and diatomaceous earth and a construction material or clay, which is hardened by a setting hardener such as cement or gypsum, and by then burning a resultant mixture. A diatomaceous earth based moisture control construction material is proposed in Japanese Unexamined Patent Publication No. 4-354514 Official Gazette. A zeolite based moisture control construction material is proposed in Japanese Unexamined Patent Publication No. 3-109244 Official Gazette.
There have been provided no moisture control construction materials which are fired and are glazed at the surfaces thereof. This is because of the facts that, as a result of glazing the moisture control construction materials, the surfaces thereof are covered with glass layers of glaze and that such construction materials lose moisture control capability.
Thus, to ensure moisture control capability, glaze is not applied to the conventional moisture control construction materials. Consequently, the conventional moisture control construction materials have not been decorated by various kinds of decorating methods, so that the materials have small kinds design. The conventional construction materials lacking a glazed surface are easily stained by, for instance, handling, and stained construction materials are hard to be cleaned.
Accordingly, the present invention aims at solving drawbacks of the conventional construction materials, and at providing a moisture control material enhanced in decorativeness and improved in stain-resistance by applying glaze onto the surfaces thereof.
A moisture control construction material of the present invention is a fired or burnt building material and has a feature that glaze is applied to the surface of the body of the moisture control construction material. The body has porosity of 20-50%, and more than 40% of pores of the body have a radius of less than 0.1 xcexcm.
Glazing the surface of the moisture control construction material of the present invention enables various decorations thereof through the use of glaze and widens a range of design thereof.
Moreover, the glazed surface of the moisture control construction material of the present invention is hard to be stained with, for example, finger marks. Even if the glazed surface is stained, stains are easily removed therefrom. Thus, the surface of the moisture control construction material of the present invention is kept clean.
As a result of glazing the surface of the body of the moisture control construction material of the present invention, the surface thereof is covered with a glass layer produced from glaze. Thus, the moisture absorbing and desorbing rates thereof decrease a little. Further, the moisture absorbing and desorbing capacities thereof are almost the same to those having no glazed surface. Consequently, the moisture control functions of the construction materials of the present invention are excellent without impaired by the glazed surface.
Preferably, this glazing is performed so that the glass layer produced from glaze is formed on a region whose area is not more than 90% of the area of the surface of the body of the moisture control construction material. The maximum thickness of this glass layer is preferably less than 300 xcexcm. After the surface of the moisture control construction material is glazed, it is preferable that the construction material has a moisture control performance which is more than 80% of that achieved before the surface thereof is glazed.
Preferably, the moisture-absorbing-and-desorbing-performance in each 8-hour cycle of the moisture control construction material is more than 80 g/m2. Humidity in residential buildings may change very quickly by cooking, bathing or heating or according to a variation in temperature on each day so that the moisture control construction material requires high moisture absorbing and desorbing rates. This requirement is met by setting the moisture absorbing and desorbing rates in each 8-hour cycle as more than 80 g/m2 (in the case of setting the moisture absorbing and desorbing rates in each 24-hour cycle, these rates are set as more than 140 g/m2).
The moisture-absorbing-and-desorbing-performance in each 8-hour cycle is determined as follows. First, in a steady-temperature-and-humidity chamber in which relative humidity is maintained at 50%, a test sample is set so that the weight thereof is substantially constant (namely, a variation in weight thereof is less than 0.1%). Then, this test sample is quickly put into another steady-temperature-and-humidity chamber in which a relative humidity is maintained at 90%. An increase in weight (namely, an amount of absorbed moisture in gram) thereof, which is measured 8 hours later, is expressed as a value thereof per unit area (1 m2). This value is determined as an amount of moisture absorbed during 8 hours.
An amount of moisture desorbed during 8 hours is obtained as follows. First, in a steady-temperature-and-humidity chamber in which a relative humidity is maintained at 90%, a test sample is set so that the weight thereof is substantially constant (namely, a variation in weight thereof is less than 0.1%). Subsequently, this test sample is quickly put into another steady-temperature-and-humidity chamber in which a relative humidity is maintained at 50%. A decrease in weight (namely, an amount of desorbed moisture in gram) thereof, which is measured 8 hours later, is expressed as a value thereof per unit area (1 m2). This value is determined as an amount of moisture desorbed during 8 hours. Then, the moisture-absorbing-and-desorbing-performance is obtained by the following equation:
(The moisture-absorbing-and-desorbing-performance in 8-hour cycle)={(the amount of moisture absorbed during 8 hours)+(the amount of moisture desorbed during 8 hours)}/2. 